A novel retractable trocar thoracostomy system is needed to replace the current needle thoracostomy technique that is used in emergency situations for patients who have tension pneumothorax, and to replace current chest tube insertion devices and procedures, as well as laparoscopic procedures. A retractable trocar should be quicker, easier and less traumatic than currently used techniques, provided, among other criteria, that the cutting mechanism used to enter the chest is designed not to injure deep structures.